Background-The decay of the pressure gradient across a stenotic mitral valve is determined by the size of the orifice and net AV compliance (C n ). We have observed a group of symptomatic patients, usually in sinus rhythm, characterized by pulmonary hypertension (particularly during exercise) despite a relatively large mitral valve area by pressure half-time. We speculated that this discrepancy was due to low atrial compliance causing both pulmonary hypertension and a steep decay of the transmitral pressure gradient despite significant stenosis. We therefore tested the hypothesis that C n is an important physiological determinant of pulmonary artery pressure at rest and during exercise in mitral stenosis. Methods and Results-Twenty patients with mitral stenosis were examined by Doppler echocardiography. C n , calculated from the ratio of effective mitral valve area (continuity equation) and the E-wave downslope, ranged from 1.7 to 8.1 mL/mm Hg. Systolic pulmonary artery pressure (PAP) increased from 43Ϯ12 mm Hg at rest to 71Ϯ23 mm Hg (range, 40 to 110 mm Hg) during exercise. There was a particularly close correlation between C n and exercise PAP (rϭϪ0.85).Patients with a low compliance were more symptomatic (PϽ0.025). Catheter-and Doppler-derived values for C n , determined in 10 cases, correlated well (rϭ0.79). Conclusions-C n , which can be noninvasively assessed, is an important physiological determinant of PAP in mitral stenosis. Patients with low C n represent an important clinical entity, with symptoms corresponding to severe increases in PAP during stress echocardiography.

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Absence of early ST segment elevation resolution after angiographically successful primary PTCA identifies patients who are less likely to benefit from the early restoration of flow in the IRA, probably because of microvascular damage and subsequently less myocardial salvage.